[PATCH] D144708: [clangd] Fix UB in scanPreamble

[Haojian Wu via Phabricator via cfe-commits]

hokein accepted this revision.
hokein added inline comments.
This revision is now accepted and ready to land.


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Comment at: clang-tools-extra/clangd/Preamble.cpp:351
   auto PreambleContents =
-      llvm::MemoryBuffer::getMemBufferCopy(Contents.substr(0, Bounds.Size));
+      llvm::MemoryBuffer::getMemBufferCopy(PI.Contents.substr(0, Bounds.Size));
   auto Clang = prepareCompilerInstance(
----------------
Looks like we have an extra cost here -- the std::string.substr will construct a new string everytime, we could save it by using `llvm::StringRef(PI.Contents).substr(0, Bounds.Size)`.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D144708/new/

https://reviews.llvm.org/D144708